Electro-optical materials, which change their optical appearance upon application of an electrical field, have been developed for use with different optical devices, including eyewear, protective goggles, visors, automotive mirrors, windows, etc. Liquid crystal materials are commonly used but other electro-optic materials show promise.
In the case of eyewear, such as goggles and visors, it will be appreciated that a number of problems are realized in attempting to incorporate a liquid crystal device into a prior art eyewear frame. Indeed, given the basic form and construction of a liquid crystal device or any device which uses an electro-optic material that can be used in a lens, special features must be incorporated into an eyeglass frame to accommodate such a lens. As will be understood by a skilled artisan, liquid crystal and other electro-optic lenses have an edge seal wherein a glue or adhesive bead with different electro-optical properties than the active area—the area containing the electro-optic material—is provided. It will be appreciated that it is desirable to hide the edge seal within the eyewear frame. Moreover, these types of lenses require protruding tabs to serve as electrodes for allowing application of a desired electrical waveform or voltage to the electro-optic material. Accordingly, the device, the edge seal, and/or the electrode tabs are typically not robust enough to survive insertion into an elastically deformed frame. This is especially true in sunglasses which do not employ a carrier lens. In other words, in generally ophthalmic eyewear applications, a corrective lens is provided which provides a substantial carrier or base to which the liquid crystal device may be attached. As such, the rigidity of the carrier is able to withstand the forces required to insert the lens into the eyewear. However, a liquid crystal lens or similar lens, by itself, cannot withstand such forces. It will further be appreciated that the electro-optic lenses require batteries, drive circuits, switches and other interconnecting conductors for operation. These components must be located somewhere in or on the frame while maintaining an aesthetically pleasing appearance or indeed, be totally unobservable by the wearer or the casual observer. Similar issues may be encountered when attempting to incorporate an electro-optically active material within an optical device such as an automotive mirror, etc.
One aspect of liquid crystal cells that have proven to be problematic is the interface of the liquid crystal (LC) cell electrodes which are used to apply an electric field to the liquid crystal material. Past LC cells required each electrode to be patterned with a special tab to which some type of conductor, e.g. wire or tape, was used for interconnection to a control circuit. Although such an approach was workable, it has been found to be difficult to implement for manufacturing a large number of cells in devices such as eyewear, scopes or mirrors. And such an interconnection was found to be somewhat unreliable and susceptible to breakage. Moreover, the need to form a tab hinders the ability to extend the electro-optically active material to peripheral edges of the cells. Additionally, some cell designs have used small amounts of conductive materials (adhesives) as so-called “crossover dots” to electrically connect the electrode of one substrate to a separate conductive tab on the opposing substrate. As such, crossover dots further complicate cell design and provide another point for device failure. A further drawback of cell designs employing crossover dots is that if the cell is found to be defective, it cannot be easily repaired because it cannot be easily disconnected from the electronic control circuit.
Based upon the foregoing problems, it will be appreciated that there is a need for an improved interconnection of electro-optic cells within optical devices. Indeed, there is a need for optical cell interconnections that do not require special patterning of the electrode layers on the cells. And there is a need for an interconnection that is flexible and robust.